If both shafts are rigidly mounted, and you have good traction on the mateing surface, what you have is a gear reduction.
This was a somewhat common way for the old slow water wheels to speed up the shafts in the mill.
They would have gear teeth on the inside of the outside rim that would mesh with a gear on a shaft going through the mill wall.
20 to 1 ratios were common (20 foot wheel and 1 foot shaft gear)
This was an alternative to having the wheel axel come trough the wall and doing the speed up inside.